In urine, Osteoactivin GSTA-1, Renin, IP-10, and RBP4 were the top 5 ranked proteins that differentiated healthy control subjects from AKI patients (Fig. 2A,B), whereas β2-microglobulin, TFF3, MCP-1, GSTA1 and EGF were the top proteins that differentiated healthy control subjects from those with CKD/ESKD (Fig. 2C,D). This evidence concerns the gene RBP4 and acute kidney injury.